It's Halloween in Tyria, and the Mad King has returned. Starting today, all Guild Wars 2 players will log in to find a ton of new content in the MMO, from holiday-themed decorations to transformative costumes all the way up to whole new areas, mini-dungeons, and bosses. Some of these events will only happen for the duration of the event, and will vanish on October 31st. But many more of them will linger on, evidence of ArenaNet's ongoing commitment to constantly adding new content to their already massive game.

Last week I met with Matt Wuerffel and Mike Zadorojny, both of whom are designers working on adding new content to Guild Wars 2. They walked me through a lot of the new stuff in the game. I also spent a little bit of time this weekend running around the new content on the developers' server—less than I would have liked, as I didn't anticipate that it'd take most of the day to download the entire developers' build of the game, but still long enough to see what's what. I gotta say: For a free content drop, the Halloween stuff is above and beyond.

The Mad King-themed Halloween stuff is a trip, and from what I saw, a lot of fun. Players will be able to hack apart various trick-or-treat themed items—including giant candy corns—and craft a bunch of unique Halloween-themed items. Some areas, Lion's Arch in particular, have been completely redone for the holiday—the city is now tinged with green and festooned with Halloween decorations, and there's a giant green cauldron in the middle of the square that, if you can climb up and jump in, will turn you into one of a number of Halloween-themed monsters. I've only seen a few of these, but my favorite was the plastic spider, which scoots around as if pushed by an imaginary hand.

The Mad King storyline will play out similar to, actually, Oblivion's oblivion gates. (That's putting it into language that non-hardcore MMO players like me will understand.) At various places in the world, doors will crop up, which begin by pouring enemies out into the world but eventually lead through to the Mad King's dimension, where you'll engage in several different creative challenges. The events will change to coincide with the various phases in the planned festivities (there are four in total—they stack on top of each other and open up new content, culminating with a big Halloween fest of events).

But there's also a bunch of new content that has nothing to do with Halloween. The mini-dungeons are a cool idea—they're nowhere near as involved and massive as the game's full-on dungeons; they're just hidden areas in the world that open up into collections of challenges and battles that are pretty intense, but still the kind of thing you could tackle in an hour or two.

The mini-dungeon I saw involved a devious platforming puzzle over lava, leading into an Asura named Vexa's testing lab. In addition to the lava jumping puzzle, players would have to bypass a complicated Portal-esque puzzle room, navigate a high-wire act while dodging unkillable patrol drones, and eventually take on Vexa herself, dressed in a giant golem suit on a platform floating above a huge tank of sharks. Yeah. The whole thing looked shockingly difficult (Wuerffel repeatedly broke the rules to hurry through it and show me everything), but at the same time, a good middle-ground between Guild Wars 2's massive proper dungeons and its contained dynamic events.

There are a lot of other new kinds of content to be discovered throughout the world—ArenaNet are big on letting players find stuff for themselves, and so I only saw a fraction of it. One of my favorite are a "guild" of computer-controlled NPCs called "Modus Sceleris" who you'll have to face down and fight, and a Skritt Burglar who sometimes pops out of treasure chests and must be chased down in order to get his loot. (The closest analogue to this is the treasure goblin in Diablo III.)

The best thing about all of this was that Wuerffel and Zadorojny assured me this was the first monthly content drop of many, and that they're already getting November's new content ready. I have a hard time wrapping my head around this— Guild Wars 2 already feels so huge that I'll never see a fraction of it, and every month from here on out, it'll just be getting bigger. The new content goes live today, October 22, so head back into Tyria and have good trick-or-treating!